Shear for forming rounded corners on rectangular cards, etc.



May 17, 1960 A. NAFFIN HEAR FOR FORMING ROUNDED CORNERS 0N RECTANGULAR CARDS, ETC.

Filed July 26, 1957 11a. Z E6. 6.

INVENTOR.

ATTORNEY United States Patent SHEAR FOR FORMING ROUNDED CORNERS ON RECTANGULAR CARDS, ETC.

Alfred Naflin, Santa Monica, Calif.

Application July 26, 1957, Serial No. 674,365

2 Claims. (Cl. 83-583) This invention relates to a device for forming rounded corners on rectangular sheet material and has as its, primary object the provision of a shear which is so constructed and operated as to eifect a slicing action in: wardly on an arcuate path from the adjacent perpendicular edges forming the corner of a rectangular sheet, whereby the device is rendered particularly adapted for use in rounding the corners of laminated sheets embodying,

layers of cast acetate, and whereby formation of a smooth accurate curved edge is insured.

Another object is to provide a shear embodying a vertically reciprocal blade so formed as to effect a slicing action on downward rectilineal movement thereof and wherein such slicing action occurs co-incidently and progressively from opposed spaced points toward and to a meeting point to present balanced opposing lateral thrusts on sheet material being severed and thereby insure against bodily displacement of the sheet material by the shear during the severing operation.

A further object is to provide a substantial mounting for the shearing blade and its associated parts, and also to provide a construction whereby the device may be readily assembled and easily operated.

With the foregoing objects in view together with such other objects and advantages as may subsequently appear, the invention resides in the parts and in the combination, construction and arrangement of parts hereinafter described and claimed, and illustrated by way of example in the accompanying drawing in which:

Fig. 1 is a plan view of the device depicting the manner of mounting same;

Fig. 2 is an enlarged View in elevation taken on the line 2-2 of Fig. 1 as seen in the direction indicated by the arrows;

Fig. 3 is a view in section and elevation taken on the line 33 of Fig. 2 showing the reciprocal shear in its elevated position;

Fig. 4 is a view similar to Fig. 3 showing the shear in its depressed position;

Fig. 5 is a detail in horizontal section and plan taken on the line 55 of Fig. 4;

Fig. 6 is a view in section as seen on the line 6-6 of Fig. 4;

Fig. 7 is a view in front elevation of the shear element showing it detached; and

Fig. 8 is a view in section as seen on the line 8-8 of Fig. 7.

Referring to the drawings more specifically A indicates generally a fiat base panel such as the rectangular panel of a conventional hand operated paper cutter. The base A has a forty-five degree diagonal margin B afforded by eliminating a corner of the rectangular panel and which margin carries a rectangular housing C which is aifixed to the panel A by screws D and projects upwardly from the upper face of the panel A. The housing C, here shown as formed of a block of metal, has on the face thereof presented to the panel A, a transversely extending elongated slot E of rectangular outline. The

slot E has vertical side walls ab which converge inwardly in perpendicular right angular relation to each other so as to form abutments for the adjacent margins of a rectangular sheet or card F or the like on insertion of the corner portion of such sheet or card into the slot E as shown in Fig. l. The lower margin 0 of the slot E extends on a plane slightly above the top surface of the panel A which margin c is beveled or rounded so that the sheet or card F sliding on the panel A may be readily directed into the slot E.

The housing C has a cylindrical bore :1 extending ver-. tically therethrough midway of its side margins which bore intersects the slot E, and slidably mounted in the bore d is a cylindrical tubular plunger G fitted with a cap H on its upper end which plunger is normally sustained in an elevated position by an expansion coil spring I which bears between a pin K on the housing C and the underside of the cap H, The pin K extends horizontally into the housing C from one side thereof across the bore d and plunger G which latter is formed with an elongated slot L through which the pin K extends and which slot permits longitudinal movement of the plunger G relative to the housing C.

The lower end of the plunger G is formed with a cutter comprising a fixed blade M embodying a pair of downwardly extending prongs 1 which diverge relative to each other and terminate in points g. The prongs have.

a downwardly presented continuous cutting edge e of general inverted U-shaped longitudinal contour and curved laterally in conformity with the curvature of the inner periphery of the plunger D. The portion e of the cutting edge e leading from the base portion of each prong f to the other is of arched or arcuate formation. The outer margins of the prongs f extend above the arcuate intermediate portion e of the cutting edge e to a point of intersection with the lower end of the plunger G which end inclines upwardly from the base portion of the blade M toward the forward portion of the plunger G; the blade M being formed on the rear portion of the plunger.

Pivotally mounted in the lower end of the bore d is an upwardly extending metallic cylindrical shear element N having an arcuate edge It on its upper end which is presented to the cutting edge e of the blade M, the margin h and cutting edge e being designed to conform to each other and to co-act to effect a shearing action when the blade M is advanced relative to the element N. In order to insure such shearing action the element N is pivotally supported at its lower end on a pivot pin 0 mounted in the housing C and extending across the bore d adjacent the lower end thereof, the element N being thus mounted for swinging movement against the adjacent faces of the prongs f. A spring P bears between the forward upper end portion of the element N and the adjacent wall of the bore d to press the margin h tightly against the cutting edge e on the blade M.

The upper end of the element N lies on a. plane slightly below the lower margin of the slot B so that a sheet or card F inserted in the slot will overlie the upper end of the element N. The major portion of the cutting edge ee' normally extends above the upper end of the element N a distance such that the corner of the sheet or card F inserted in the slot E with the side edges thereof abutting the sides ab of the slot will extend between the prongs f of the blade M such that on depressing the latter the corner of the sheet or card will be severed and rounded as indicated in Fig. 5.

In the operation of the invention on inserting a sheet or card F in the slot E as above stated the plunger G is depressed in opposition to the spring I from the position shown in Fig. 3 to that shown in Fig. 4 thus advancing the cutting blade M so as to effect severance of the corner portion of the card or sheet.

Patented May 17, 1960 V cent side'marginofthe sheet or card F with each of the prongs j performing a slicingaction' along the'arcuate margin h in opposite directions while advancing downwardly through the material of the sheet or card F until the-central arcuate portion -e' of the cutting edge e is advanced through the material past the margin h. By this action the sheet F is held against displacement during the cutting action and a clean accurate severance of the corner is assured. 1

On completion of the cutting action which occurs on termination of the downstroke of the plunger G the latter on being relieved of downward pressure will be restored to its normal uppermost position by the spring I and is then in readiness for another operation.

While a specific embodiment of the invention has been shown and described, the invention is not limited to the exact details of construction set forth, and the invention embraces such changes, modifications and equivalents of the parts and their formation and arrangement as come within the purview of the appended claims.

- I claim:

1. In a shear for forming rounded corners on flat rectangular material, a flat base panel, a block fixed on a margin of said panel and projecting upwardly therefrom, said block having a transverse slot extending proximate the top surface of said panel, said slot having opposed side walls converging at right angles to each other and forming ,abutments for the adjacent margins of a corner portion of a rectangular sheet to be rounded, said block having a vertical cylindrical bore intersecting the inner absenceportion of said slot, a reciprocal tubular plunger guided in said bore having a closed upper end and an open lower end, spring means in said plunger normally supporting it in an elevated position, a blade fixed on the lower end of said plunger embodying a pair of downwardly diverging prongs having shearing edges extending along their inner margins connected in continuation of each other on an arc at the bases of said prongs, said prongs being. disposed on the side of said plunger opposite said' slot' and being transversely curved throughout on the inner faces thereof, and a cylindrical shear element supported in saidbore having an arcuate upper margin bearing against and conformable to theinner 'faces 'of' said of saidprongs' spaced above the upper end ofsaid element.

2. The structure called for in claim 1 in which said shear element is pivotally-supported adjacent its lower end to swing toward said prongs, and a spring bearing between the upper forward end portion of said shear element to thrust the arcuate upper margin thereof against the inner faces of said prongs.

References Cited in the file of this patent UNITED STATES PATENTS 1,319,662 2,082,867 Anderson June8, 1937 2,163,868 Christie June 27, 1939.

2,259,351 Oberholser et al. Oct. 14, 1941 Traub Oct. 21, 1919 

